Prehistoric Eurasians streamed into Africa, genome shows
Africa is the birthplace of our species and the source of ancient migrations that spanned the globe. But it has missed out on a revolution in understanding human origins: the study of ancient DNA. Although researchers have managed to sequence the genomes of Neandertals from Europe, prehistoric herders from Asia, and Paleoindians from the Americas, Africa's hot and humid climate has left little ancient DNA intact for scientists to extract. As a result, “Africa was left out of the party,” says anthropological geneticist Jason Hodgson of Imperial College London.
Until now. A paper published online this week in Science (http://scim.ag/MGLlorente) reveals the first prehistoric genome from Africa: that of Mota, a hunter-gatherer man who lived 4500 years ago in the highlands of Ethiopia. Named for the cave that held the remains, the Mota genome “is an impressive feat,” says Hodgson, who was not involved in the work. It “gives our first glimpse into what an African genome looked like prior to many of the recent population movements.” And when compared with the genomes of living Africans, it implies something startling. Africa is usually seen as a source of outward migrations, but the genomes suggest a major migration into Africa by farmers from the Middle East, possibly about 3500 years ago. These farmers' DNA reached deep into the continent, spreading even to groups considered isolated, such as the Khoisan of South Africa and the pygmies of the Congo
Ancient Ethiopian genome reveals extensive Eurasian admixture throughout the African continent
Characterizing genetic diversity in Africa is a crucial step for most analyses reconstructing the evolutionary history of anatomically modern humans. However, historic migrations from Eurasia into Africa have affected many contemporary populations, confounding inferences. Here, we present a 12.5x coverage ancient genome of an Ethiopian male (‘Mota’) who lived approximately 4,500 years ago. We use this genome to demonstrate that the Eurasian backflow into Africa came from a population closely related to Early Neolithic farmers, who had colonized Europe 4,000 years earlier. The extent of this backflow was much greater than previously reported, reaching all the way to Central, West and Southern Africa, affecting even populations such as Yoruba and Mbuti, previously thought to be relatively unadmixed, who harbor 6-7% Eurasian ancestry
مواضيعك غير عربيه
معرفك أيضا غير عربى
تذكرت مقطع من الفلم الرائع amistad
عندما قال الرجل لصاحبه
you are acting like white man,nigga
هذه الدراسة حديثة ومهمة يا أبو أثير
نشرت بتاريخ 8\10\2015 وأهميتها تكمن في أنه لأول مرة يتم استخلاص الحمض النووي من جمجمة عمرها حوالي 4500 سنة من افريقيا, تم العثور عليها من بقايا رجل في كهف بمرتفعات اثيوبيا
ونتائج هذه الدراسة تشير الى حدوث موجة هجرة عظيمة للمزارعين من الشرق الاوسط الى افريقيا ربما من حوالي 3500 سنة.
هذا لب الموضوع ومن الملاحظ الاهتمام الكبير من المواقع العلمية ووسائل الاعلام بهذه الدراسة..
Understanding human genetic diversity in Africa is important for interpreting the evolution of all humans, yet vast regions in Africa, such as Chad, remain genetically poorly investigated. Here, we use genotype data from 480 samples from Chad, the Near East, and southern Europe, as well as whole-genome sequencing from 19 of them, to show that many populations today derive their genomes from ancient African-Eurasian admixtures. We found evidence of early Eurasian backflow to Africa in people speaking the unclassified isolate Laal language in southern Chad and estimate from linkage-disequilibrium decay that this occurred 4,750–7,200 years ago. It brought to Africa a Y chromosome lineage (R1b-V88) whose closest relatives are widespread in present-day Eurasia; we estimate from sequence data that the Chad R1b-V88 Y chromosomes coalesced 5,700–7,300 years ago. This migration could thus have originated among Near Eastern farmers during the African Humid Period. We also found that the previously documented Eurasian backflow into Africa, which occurred ∼3,000 years ago and was thought to be mostly limited to East Africa, had a more westward impact affecting populations in northern Chad, such as the Toubou, who have 20%–30% Eurasian ancestry today. We observed a decline in heterozygosity in admixed Africans and found that the Eurasian admixture can bias inferences on their coalescent history and confound genetic signals from adaptation and archaic introgression